[syn: mysterious, mystic, mystical, occult, secret, orphic]
The Collaborative International Dictionary of English v.0.48:
Mystic \Mys"tic\, Mystical \Mys"tic*al\, a. [L. mysticus, Gr. ?
   belonging to secret rites, from ? one initiated: cf. F.
   mystique. See 1st Mystery, Misty.]
   1. Remote from or beyond human comprehension; baffling human
      understanding; unknowable; obscure; mysterious.
      [1913 Webster]
            Heaven's numerous hierarchy span
            The mystic gulf from God to man.      --Emerson.
      [1913 Webster]
            God hath revealed a way mystical and supernatural.
                                                  --Hooker.
      [1913 Webster]
   2. Importing or implying mysticism; involving some secret
      meaning; allegorical; emblematical; as, a mystic dance;
      mystic Babylon.
      [1913 Webster]
            Thus, then, did the spirit of unity and meekness
            inspire every joint and sinew of the mystical body.
                                                  --Milton.
      [1913 Webster]
   3. employing mysticism; as, mystical intuition; mystical
      explanations; -- contrasted to logical, rational,
      analytical.
      [WordNet 1.5] -- Mys"tic*al*ly, adv. --
      Mys"tic*al*ness, n.
      [1913 Webster]
WordNet (r) 3.0 (2006):
mystical
    adj 1: relating to or characteristic of mysticism; "mystical
           religion" [syn: mystic, mystical]
    2: relating to or resembling mysticism; "mystical intuition";
       "mystical theories about the securities market" [syn:
       mystic, mystical]
    3: having an import not apparent to the senses nor obvious to
       the intelligence; beyond ordinary understanding; "mysterious
       symbols"; "the mystical style of Blake"; "occult lore"; "the
       secret learning of the ancients" [syn: mysterious,
       mystic, mystical, occult, secret, orphic]
Moby Thesaurus II by Grady Ward, 1.0:
73 Moby Thesaurus words for "mystical":
   absolute, abysmal, allegorical, anagogic, arcane,
   between the lines, cabalic, cabalistic, cabbalistic, categorical,
   clandestine, concealed, covert, cryptic, deep, delitescent, divine,
   dormant, enwrapped in mystery, epiphanic, esoteric, furtive,
   hibernating, hidden, hole-and-corner, holy, hugger-mugger,
   hush-hush, indefinable, ineffable, inexplicable, inextricable,
   insoluble, insolvable, latent, lurking, metaphysic, miraculous,
   muffled, mysterious, mystic, obfuscated, obscured, occult,
   possible, potential, preternatural, private, profound, sacred,
   secret, sleeping, sneak, spiritual, stealthy, submerged,
   supernatural, supranatural, symbolical, theosophical, theosophist,
   ultimate, unaccountable, undefinable, under the surface,
   underlying, unexplainable, uninterpretable, unmanifested,
   unrevealed, unsolvable, veiled, virtual